title: Quantification of the level of fat-soluble vitamins in feed based on the novel microemulsion electrokinetic chromatography (MEEKC) method.
abstract: BACKGROUND
  Simultaneous quantification of liposoluble vitamins is not a new area of interest, since these compounds co-determine the nutritional quality of food and feed, a field widely explored in the human and animal diet. However, the development of appropriate methods is still a matter of concern, especially when the vitamin composition is highly complex, as is the case with feed designated for laboratory animals, representing a higher health and microbiological status.
  
  
  RESULTS
  A method combining microemulsion electrokinetic chromatography (MEEKC) with liquid-liquid extraction was developed for the determination of four fat-soluble vitamins in animal feed. A separation medium consisting of 25 mmol L⁻¹ phosphate buffer (pH 2.5), 2-propanol, 1-butanol, sodium dodecyl sulfate and octane allowed the simultaneous determination of vitamins A, D, E and K within a reasonable time of 25 min. The polarity of the separation voltage was reversed in view of the strongly suppressed electro-osmotic flow, and the applied voltage was set at 12 kV. The fat-soluble vitamins were separated in the order of decreasing hydrophobicity.
  
  
  CONCLUSIONS
  It was proved that the proposed MEEKC method was sufficiently specific and sensitive for screening fat-soluble vitamins in animal feed samples after their sterilization.
authors.affiliation: Department of Pharmaceutical Chemistry, Medical University of Gdańsk Ul., Gen. J. Hallera 107, PL-80-416, Gdańsk, Poland.
authors.forename: Ilona
authors.initials: I
authors.lastname: Olędzka
authors.forename: Piotr
authors.initials: P
authors.lastname: Kowalski
authors.forename: Alicja
authors.initials: A
authors.lastname: Bałuch
authors.forename: Tomasz
authors.initials: T
authors.lastname: Bączek
authors.forename: Jolanta
authors.initials: J
authors.lastname: Paradziej-Łukowicz
authors.forename: Marcin
authors.initials: M
authors.lastname: Taciak
authors.forename: Barbara
authors.initials: B
authors.lastname: Pastuszewska
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000818:Animals; D002845:Chromatography / Q000379:methods*; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D009753:Nutritive Value; D012995:Solubility; D014801:Vitamin A / Q000032:analysis; D014807:Vitamin D / Q000032:analysis; D014810:Vitamin E / Q000032:analysis; D014812:Vitamin K / Q000032:analysis; D014815:Vitamins / Q000032:analysis* / Q000145:classification
chemical_list: D014815:Vitamins; D014801:Vitamin A; D014812:Vitamin K; D014807:Vitamin D; D014810:Vitamin E
keywords: fat-soluble vitamins; laboratory animal feed; liquid-liquid extraction; microemulsion electrokinetic chromatography